/**
 * rspamd 스팸 필터 서비스
 * 스팸 검사, 학습 API 연동
 */

const RSPAMD_HOST = process.env.RSPAMD_HOST || "rspamd";
const RSPAMD_PORT = process.env.RSPAMD_PORT || 11333;
const RSPAMD_BASE_URL = `http://${RSPAMD_HOST}:${RSPAMD_PORT}`;

// 스팸 점수 임계값 (이 값 이상이면 스팸으로 분류)
const SPAM_THRESHOLD = 6.0;

/**
 * 이메일 스팸 검사
 * @param {string} rawEmail - 원본 이메일 데이터 (RFC822 형식)
 * @returns {Promise<{isSpam: boolean, score: number, action: string}>}
 */
const checkSpam = async (rawEmail) => {
  try {
    const response = await fetch(`${RSPAMD_BASE_URL}/checkv2`, {
      method: "POST",
      headers: {
        "Content-Type": "text/plain",
      },
      body: rawEmail,
    });

    if (!response.ok) {
      console.error("[rspamd] 검사 실패:", response.status);
      return { isSpam: false, score: 0, action: "no action" };
    }

    const result = await response.json();

    // action: no action, greylist, add header, rewrite subject, soft reject, reject
    const isSpam =
      result.score >= SPAM_THRESHOLD ||
      result.action === "reject" ||
      result.action === "add header" ||
      result.action === "rewrite subject";

    console.log(
      `[rspamd] 검사 결과: score=${result.score}, action=${result.action}, isSpam=${isSpam}`
    );

    return {
      isSpam,
      score: result.score || 0,
      action: result.action || "no action",
      symbols: result.symbols || {},
    };
  } catch (error) {
    console.error("[rspamd] 검사 오류:", error.message);
    // rspamd 연결 실패 시 스팸이 아닌 것으로 처리
    return { isSpam: false, score: 0, action: "no action" };
  }
};

/**
 * 이메일을 스팸으로 학습
 * @param {string} rawEmail - 원본 이메일 데이터
 * @returns {Promise<boolean>}
 */
const learnSpam = async (rawEmail) => {
  try {
    const response = await fetch(`${RSPAMD_BASE_URL}/learnspam`, {
      method: "POST",
      headers: {
        "Content-Type": "text/plain",
      },
      body: rawEmail,
    });

    if (!response.ok) {
      console.error("[rspamd] 스팸 학습 실패:", response.status);
      return false;
    }

    const result = await response.json();
    console.log("[rspamd] 스팸 학습 완료:", result);
    return result.success !== false;
  } catch (error) {
    console.error("[rspamd] 스팸 학습 오류:", error.message);
    return false;
  }
};

/**
 * 이메일을 정상 메일(ham)로 학습
 * @param {string} rawEmail - 원본 이메일 데이터
 * @returns {Promise<boolean>}
 */
const learnHam = async (rawEmail) => {
  try {
    const response = await fetch(`${RSPAMD_BASE_URL}/learnham`, {
      method: "POST",
      headers: {
        "Content-Type": "text/plain",
      },
      body: rawEmail,
    });

    if (!response.ok) {
      console.error("[rspamd] 햄 학습 실패:", response.status);
      return false;
    }

    const result = await response.json();
    console.log("[rspamd] 햄 학습 완료:", result);
    return result.success !== false;
  } catch (error) {
    console.error("[rspamd] 햄 학습 오류:", error.message);
    return false;
  }
};

/**
 * rspamd 상태 확인
 * @returns {Promise<boolean>}
 */
const checkHealth = async () => {
  try {
    const response = await fetch(`${RSPAMD_BASE_URL}/ping`, {
      method: "GET",
    });
    return response.ok;
  } catch {
    return false;
  }
};

/**
 * 이메일 객체를 RFC822 형식으로 변환
 * @param {Object} email - 이메일 객체 (from, to, subject, text, html)
 * @returns {string}
 */
const buildRawEmail = (email) => {
  const boundary = "----=_Part_" + Date.now();
  let raw = "";

  raw += `From: ${email.from || "unknown@unknown.com"}\r\n`;
  raw += `To: ${email.to || "unknown@unknown.com"}\r\n`;
  raw += `Subject: ${email.subject || "(no subject)"}\r\n`;
  raw += `Date: ${
    email.date ? new Date(email.date).toUTCString() : new Date().toUTCString()
  }\r\n`;
  raw += `Message-ID: ${email.messageId || `<${Date.now()}@local>`}\r\n`;
  raw += `MIME-Version: 1.0\r\n`;

  if (email.html) {
    raw += `Content-Type: multipart/alternative; boundary="${boundary}"\r\n\r\n`;
    raw += `--${boundary}\r\n`;
    raw += `Content-Type: text/plain; charset=utf-8\r\n\r\n`;
    raw += `${email.text || ""}\r\n`;
    raw += `--${boundary}\r\n`;
    raw += `Content-Type: text/html; charset=utf-8\r\n\r\n`;
    raw += `${email.html}\r\n`;
    raw += `--${boundary}--\r\n`;
  } else {
    raw += `Content-Type: text/plain; charset=utf-8\r\n\r\n`;
    raw += `${email.text || ""}\r\n`;
  }

  return raw;
};

module.exports = {
  checkSpam,
  learnSpam,
  learnHam,
  checkHealth,
  buildRawEmail,
  SPAM_THRESHOLD,
};